Hammer rock drill



H. s. POTTER HAMMER Rocx DRLL Original Filed Feb. 26. 1925 l Jan. 24, 1928.

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, UNITED .STATES PATE-NT. OFFICE.

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original animation ined rebaafy 2e, 192,5, serial N0. '11,'126, and in the Union of seam Aafnam no vmber 3, 1924. Divided and this applieationled Decemberl'?, 192.5. Serial Ho. 76,123.

by means of-longitudinalr llutes 18, 19 formed. on the shank and said ch'uck portion respecvThe present invention refers to hammer rock drills in-which the hollow drill tool is so mounted in the chuck of the machine as to be rotated thereby, whilst being free for axial movement.

One of the purposes of the invention is to provide an improved form of chuck suitable-for use withfthe drill tool described in lapplication No."11,726, Afiled February 26th v1925, from which the present application is a division. Another purpose is to provide improved meansvfor preventing air from passing into of apneumatic rock drill. '3 is. the hammer',

the drilled hole. a A A Inthe accompanying drawings- Fig. I is apartly sectioned longitudinal view of a hammer rock 'drill embodying the invention. Y

Fig. II is a similar but enlarged: view of a portion thereof, the joint `between the` shank and stem being shown in section and after the parts are weldedtogether. Y

. III is a cross section on III-III of In the drawings 2 indicates the cylinder piston working in the cylinder, and having a forwardly extending nose 4'which strikes the drill' tool 5, 6,l 7;

(The tool is supported at its rear end in the4 tool chuck 8, 8*. The latter is mounted in the casing 9 of the rock drill so as to be rotatable; and it is rotated inthe example shown by the hammer piston 3, the nose. 4

' of which is vfor this purpose provided with longitudinal flutes 10 co-operating with similar iiutes 11, in the interior of the chuck portion 8*. The hamm/er itself'is caused to rotate bythe engagement of aratchet mech- I anism 12 with helical flutes 13 on the ham mer. This ratchet mechanism is of any approved'construction. 14y is the usual axial water tube which passes water into the bore 15 of the drill tool,'or delivery at the cutting end of the tool. v y

The drillstool comprises the stem 5 at the forward end of which is vformed the cutting edges 16, 'the circumferential projection 6 which bears on the front end of the lchuck 8l and lililits the penetration of the tool'nto the chuck 8,` and the shank 7 which seats .in

and is engaged rotationally by the chuck.

Thestem 5 is preferabl tapered forwardly; The shank 7 is of cy indrical formfand it'engages the chuck ,portion 8 for rotation,

shanks'eats in said seatings and is thereby held accurately in the axis of the machine.

This form of shank 'is preferably a Sep-'- ara-te part which is accurately machined during manufacture'andis subsequently welded v to the stem 5 at 23 but the stern 5 may be secured permanently to the shank 7' in any other approved way. Bein separately man: uatured it can be made o greater diameter than the stem whilst its bore 22 can be con siderably larger in diameter than the bore 15 of the stem, and of ample diameter to accommodateA the water' tube ,14. Alsdtle true seating of the shank in the chuck keeps the shank ore and the water tube always co-axial with one another.- Consequently the water tube can without danger be taken right l through the shank as shown, so that it 'projectsthe water well intothe'bore 15 of the stem and leakage rendered diicult.

The chuck is shown in are connected by dog clutch teeth 26; 4the intention being that'standardized front portions 8 should be supplied which suit the of water backwards isV itwo parts whichJ above described drill Shanks and atthesame time can be ittedto rear' portions 8aL suitable for the Vparticular ,kind of rock drill; the

said rear portions being 'specially made for the purpose by the drill maker or bein formed from lexisting chucks. The` chc portion 8 with its ribs 20 maybe cast in suitable metal,' machinin being limited to thefoutside and end sur aces and the seat Y ings 21, so that this chuckportion may be cheaply replaced when it fails to hold the drill Aproperly inline.

In some hammer drills, air from the' cyljnv l der is allowed to pass into the tool borelwith thewater to assist in clearing'thebore hole in the rock. To prevent an undue quantity of air passing down b` `reason of the large space provided by this lnvention between the water tube and the bore, said space may be obstructed by for instance an enlarement on the tube such as that indicated y 27. Y The enlargement shown 1s intended to pre.

vent the passage of air altogether, Leo that the borehole is cleaned by water only; and

to that end it consists of a rubber sleeve searound the tube.

shank.v The sleeve 27 projects beyond'th'e end-of the water tube and terminates in a conical nozzle. Owing to the wide bore of the shankpermitting the water tube to ex tend well forward the sleeve 27 is readilyV accessible from the mouth of the Vdrill casing for' replacement when necessary. v.

The sleeve 27 is retained in place by gripping into an yannular recess 28 formed Said recess is formed by pressing in the metal of the tube, the

pressed-in 'ring contracting the stream of water 'as it leaves the tube so assisting to form said stream into a compact and non expanding jet which'readily asses down to the tool bore with minimum o 'ss of energy.

The possibility of air leaking into the water is further minimized bycarrying the channels 29^^from the fronteiids of the chuck flutes 19 to the front end of the chuck with their forward ends clear of the tool collar 6 so that any air under pressure in the chuck cavity 30 may readily escape along the flutes to the open front cud of the chuck casing. 1 y a eThe escape of air lfrom the cylinder 2 to the chuck cavity 3() along the piston nose is minimized by-forming a groove 31`in the front head of the machine and connecting saidgroove by a hole 32 witlithe neck 33 of an ejector 34. Exhaust air from the ma-. VVhine is passed by the passages 35 into said ejector, reducin'gthepressure in the hole 32 and the groove '3'1 and. so withdrawing air which may be leaking along the piston nose.

The Ahole 36 produced in rock by a percussive drill tapers inwardly owing to the wear of the wings of the drill tool and,fif several A4tools are employed, in succession, owing to their being of decreasing gauge.

The tapered vsteel here shown approximates to this form of the hole', so that the cross sectional' area of the space between the tool and the wall of the hole is roughly equal throughout the length of the hole,

That is to say, the cross sectional area of the column of sludge in the hole does not vary greatly throughout its length, its

slipped over the stemof the drill.

shaust passages alternately,

bind the tool.

37 represents a rubber washer which is The tapered form of the stem resists movement of the washer rearwardly along the drill, and holds the washer in contact with the rock at the mouth of the bore hole so that it to some extent seals the latter, thus tending to keep the hole full of sludge andy maintain the sludge in a thick condition which is most, favourable for maintaining the rock chippings in suspension in the sludge and ensuring their prompt ejection from the hole without tendency to settle therein and bind the drill tool. The washer F also tends to break up any air bubbles in the sludgev and prevent them from discharging their contained dust into the atmosphere.

I claim :4-

l. In a rock drill, a cylinder provided with an exhaust assage for air, a hammer piston slidable 1n the cylinder and provided with. a nose, ia front head for the cylinder fitting around the nose and having a circumferential air groove provided with an air escape passage, andan ejector tube having its the said exhaust passage and Vhaving its front or outlet part connected with the said air escape passage and operating to eject 'the air from it.

2. In a rock drill, a cylinder provided with an exhaust passage at each end, a hammer piston which uncovers the cylinder exsaid piston being provlded with a nose, a front head for the cylinder fitting around the said nose and having a circumferential air' groove pro vided with an air escape passage, and an yejector tube receiving yair from the said exhaust passages and having an air passage at' its delivery end portion which communicates with the said air escapey passage and operates to eject air from tlie ejector tube.

' HENRY SAMUEL POTTER.

rear part communicating with 

